The present invention relates to ballast broom (also called sweepers) for sweeping the ballast on railroad tracks. More specifically, the present invention relates to a ballast sweeper having a high degree of efficiency and an associated method.
The use of ballast sweepers in connection with maintenance of a railroad track is well known. Commonly, a plow or blade-like element is used to shape or distribute the ballast in a desired arrangement. However, when ballast is plowed or new ballast is dumped onto a railway roadbed, ballast may become disposed upon the tops of the railroad ties.
In order to evenly distribute the ballast and in order to clear ballast from the tops of the railroad ties, it is common to use a railroad maintenance machine having a rotary sweeping core with a plurality of sweeper elements or bristles such as disclosed in the present inventor's prior U.S. Pat. No. RE. 31,619 issued Jul. 3, 1984 and hereby incorporated by reference. That patent describes a particular sweeper element (also called broom element or bristle) and a method of making it. The rotary core may be mounted on the same machine as the plow blade.
The present inventor's prior U.S. Pat. No. 5,394,586 issued Mar. 7, 1995 and hereby incorporated by reference discloses a dust control arrangement and technique for such rotary core ballast sweepers.
With reference to the simplified side view schematic of FIG. 1, the common prior art technique for ballast sweeping is shown. The sweeper or broom vehicle 10 has a housing 12 and rotary core 14 with 6 rows (only some shown for ease of illustration) of broom elements 16. As the core 12 rotates counterclockwise in the view of FIG. 1 and the vehicle 10 moves rightwardly, ballast 16B is thrown by the elements 16 at a series of deflectors 18 (only one shown). The deflectors 18 cause the ballast to bounce off them and move transversely to the rail direction (rail direction is left to right in FIG. 1, whereas ballast bounces out or into the plane of view of FIG. 1). The ballast is thus moved from being on top of ties to being off the end of ties.
Although the deflector arrangement has been used over the years, it is subject to numerous disadvantages. Specifically, it requires one to go over a given section of road bed numerous times in order to remove a satisfactory portion of the ballast from the tops of the ties. Each time the machine goes over a section of road bed, it moves the ballast on tops of ties, but several passes are required to sufficiently clean the ties. The ballast may not bounce quite right and thus may be moved little or no amount in the proper direction.
The core 14 must rotate sufficiently fast that most ballast 16B will have sufficient momentum to bounce off the inclined deflector plates an adequate distance. If the core 14 rotates too slowly, the ballast won't bounce far enough. On the other hand, the high speed of rotation (for example 220 to 250 revolutions per minute) means that some ballast gets carried over the top of the core 14 and may remain on the tops of ties. (This so-called material carry over is one of the reasons that material disposal or movement is not as efficient as desirable such that multiple passes are required.)
The high speed of rotation also generates substantial noise and dust. Various steps to deal with the dust and/or noise may thus be required.